The Alcatel SpeedTouch USB modem is one of a very few non-ethernet modems with
Linux drivers. This modem is quite popular in Europe (Alcatel's home turf),
and is widely used elsewhere as well. Hats off to Alcatel!

For this to work, you will essentially need three things: the Alcatel modem
firmware and management utility (supplied directly by Alcatel in
closed source, binary form), a properly configured kernel and PPP daemon,
and the Linux modem driver and related configuration. The modem driver itself
is open source. There are currently two distinct, unrelated drivers available.

When drivers were first released, the installation process required a fair
amount of patching and rebuilding to make things work. Since then, things
have progressed, and it can now be done without any patching (see below).
How well all the pieces go together may depend on how old your Linux
installation is, the kernel and PPP versions, and possibly what patches your
vendor may have applied to their own packages. Recent Linux releases
probably have most, if not all, of this already done,
and hence you may not need to do any patching. I believe this is true of
recent SuSE, Mandrake, and Debian (and probably others as well). You still
need the Alcatel binary firmware, and a driver for the modem (if
your distro does not include this). I would suggest checking your distro's
web site, and search their archives for documents relating to this modem, and
go from there as a first step. YMMV.

One obvious requirement is a kernel with USB support. USB and ATM support are
better in recent kernels, and I would suggest if not using a very current
Linux distribution, then at least get a recent kernel. And a quick note
on kernels and patching: if using the kernel source supplied with a Linux
distribution, it is most likely very heavily patched already. Applying
patches to these can be hit or miss.

As always with Linux, there is more than one way to skin a cat. This is
true of this modem and is resulting in some confusion since there
are various documents circulating on this modem with various approaches
taken. Some are more current than others too. Keep this in mind if you run
into conflicting recommendations. Again, your distribution is probably the
best source of documents.

There are two separate driver projects for this modem. The installation
and configuration are completely different, as is the code base. Both are
open source and GPL. One is a kernel module solution, originally developed by
Alcatel, and now maintained by Johan Verrept. His HOWTO is located at http://linux-usb.sourceforge.net/SpeedTouch/howto.html.
I think most would agree that the installation of this driver is the more
complex of the two, and more than likely will require some patching (unless
your distro has already done this). But, it may have some slight performance
benefits since it runs mostly in kernel space.
This driver can potentially support both PPPoE and PPPoA connections.

The other driver is by Benoit Papillault and friends. This one has a less
complicated installation, and can be done with no
patching. All the important parts here are done in user space. For
inexperienced users, or just plain ease of use, this may well be the most painless
way to go. The home page is http://sourceforge.net/projects/speedtouch
and related docs are http://speedtouch.sourceforge.net/docs.php.
This driver can also work with 2.2 kernels (2.2.17 or later). PPPoE is not
an option with this driver at this time. This driver also does not use
the management utility that is part of the Alcatel supplied binary package.
It extracts the modem firmware, and then does its own
"management", so less dependent on proprietary code. Mandrake is
reportedly including an RPM of this driver now.

Since this modem potentially supports both PPPoE and PPPoATM connections,
which one is better? Which ever is supported by your ISP, and then
which ever works best for you! If your ISP supports both (some do and
some don't), you might try each approach and make your own decision.
There is no absolute right or wrong on such things. There are just too
many variables. Theoretically at least, PPPoA should utilize a little
less overhead and system resources.

There are other USB modems on the market that use an Alcatel chipset,
such as the Efficient Networks 4060. Do not expect either of these drivers to
work with other modems. They won't. You should get a compatible ethernet
modem in such situations. There are other USB modems with Linux drivers also.
See http://eciadsl.sourceforge.net/.